One of the seminal patents in this field is U.S. Pat. No. 3,613,894, to Clegg (“Clegg '894”), dated Oct. 19, 1971. That patent describes the use of “stop and go” (also known as “dump and go”) tanks in the fighting of rural fires. A stop and go tank is simply a portable container which is transported to the fire, filled with water from a local source, and used to dispense the water through conventional fire hoses onto the fire. When the tank is emptied, it is refilled from the local water source. This technique is a desirable alternative to the use of shuttle trucks bringing water to the site, provided that a local water source is readily available.
According to Clegg '894, a problem that exists in dump and go tanks is the entry of foreign objects into the tank when a pond, stream or the like is used as the water source. Rather than doing anything to remove these foreign objects, Clegg '894 teaches a strainer device that remains in the tank and prevents the foreign objects from entering the hose which withdraws the water from the tank. However, the Clegg '894 device operates in the rather clean conditions inside the stop and go tank, not in a sandy or gravelly stream bed or beach.
Clegg '894 discloses the need to refill the tank of a dump and go tanker as quickly as possible and even discusses the problems in the tank associated with keeping the strainer in place during the swirling and whirlpooling that can occur during periods of rapid filling of the tank.
Clegg '894 is not the only patent that describes a strainer type device for use inside a dump and go tank. Another such invention in taught in U.S. Pat. No. 4,357,238, to Ziaylek, Jr., issued Nov. 2, 1982 (“Ziaylek '238”). That invention also teaches a strainer device which seeks to position itself as low in the tank as possible and remove foreign objects from the water flowing out of the tank into a hose, keeping the foreign objects in the tank.
Interestingly, when Ziaylek later obtained a patent (U.S. Pat. No. 4,647,374, Mar. 3, 1987) (“Ziaylek '374”) describing an inlet head for removing water from a pool, pond or the like, the concept of using a strainer device that seeks the low spot in the water source was not a part of the invention. Ziaylek '374 teaches that the pumping of water from the bottom of a stream or pond may be substantially impeded if the strainer becomes clogged or covered with leaves or other debris.
While the need to keep foreign objects out of the fire hoses is certainly desired, an even more important desire is to prevent the foreign objects from ever getting into the tank in the first place. Clearly, when foreign objects enter the tank, they must eventually be removed. If they don't leave through the hoses, they will need to be cleaned out. This need not happen if the foreign objects never enter the tank.
It is desirable to prevent foreign objects from entering the tank while maintaining a high fill rate of the tank that it is at least 1500 gallons per minute, and preferably even higher.
Further limitations and disadvantages of conventional, traditional, and proposed approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.